Supplement Forms/Alternate Names

  • Red Clover Isoflavones
  • Soy Isoflavones
  • Soybean isoflavone


Isoflavones are compounds found in many different plants. They are found most in soy products. Isoflavones mimic estrogen. They have been used to ease symptoms of menopause and lower blood pressure. Isoflavones have also been used to lower the risk of some types of cancer. They can be taken as a pill or powder.


40 to 80 milligrams daily

What Research Shows

Likely Effective

May Be Effective

  • —may modestly lower risk in men and women who eat low to moderate amounts of soy J1

Unlikely to Be Effective

Not Enough Data to Assess

  • Bone health B1

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take isoflavones in small doses for a short time. Not enough studies have been done to say whether it is safe to use for a long period. Women who are pregnant or breastfeeding should not take large doses of isoflavones.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.


REFA Body Weight

REFA1 Zhang YB, Chen WH, et al. Soy isoflavone supplementation could reduce body weight and improve glucose metabolism in non-Asian postmenopausal women--a meta-analysis. Nutrition. 2013 Jan;29(1):8-14.

REFB Bone Health

REFB1 Castelo-Branco C, Cancelo Hidalgo MJ. Isoflavones: effects on bone health. Climacteric. 2011 Apr;14(2):204-211.

REFC Breast Cancer

REFC1 Fritz H, Seely D, et al. Soy, red clover, and isoflavones and breast cancer: a systematic review. PLoS One. 2013 Nov 28;8(11):e81968.

REFC2 Chen M, Rao Y, et al. Association between soy isoflavone intake and breast cancer risk for pre- and post-menopausal women: a meta-analysis of epidemiological studies. PLoS One. 2014 Feb 20;9(2):e89288.

REFD Colorectal Cancer

REFD1 Yu Y, Jing X, et al. Soy isoflavone consumption and colorectal cancer risk: a systematic review and meta-analysis. Sci Rep. 2016 May 12;6:25939.

REFE High Blood Pressure

REFE1 Taku K, Lin N, et al. Effects of soy isoflavone extract supplements on blood pressure in adult humans: systematic review and meta-analysis of randomized placebo-controlled trials. J Hypertens. 2010 Oct;28(10):1971-1982.

REFE2 Liu XX, Li SH, et al. Effect of soy isoflavones on blood pressure: a meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. 2012;22(6):463-470.

REFF High Cholesterol

REFF1 Qin Y, Niu K, et al. Isoflavones for hypercholesterolaemia in adults. Cochrane Database Syst Rev. 2013;(6):CD009518.

REFG Menopause

REFG1 Jacobs A, Wegewitz U, et al. Efficacy of isoflavones in relieving vasomotor menopausal symptoms - A systematic review. Mol Nutr Food Res. 2009 Sep;53(9):1084-1097.

REFG2 Taku K, Melby MK, et al. Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause. 2012;19(7):776-790.

REFG3 Thomas AJ, Ismail R, et al. Effects of isoflavones and amino acid therapies for hot flashes and co-occurring symptoms during the menopausal transition and early postmenopause: a systematic review. Maturitas. 2014 Aug;78(4):263-276.

REFG4 Cheng PF, Chen JJ, et al. Do soy isoflavones improve cognitive function in postmenopausal women? A meta-analysis. Menopause. 2015;22(2):198-206.

REFG5 Ghazanfarpour M, Latifnejad Roudsari R, et al. Topical administration of isoflavones for treatment of vaginal symptoms in postmenopausal women: A systematic review of randomised controlled trials. J Obstet Gynaecol. 2015;35(8):783-787.

REFG6 Li L, Lv Y, et al. Quantitative efficacy of soy isoflavones on menopausal hot flashes. Br J Pharmacol. 2015;79(4):593-604.

REFG7 Ghazanfarpour M, Sadeghi R, et al. The application of soy isoflavones for subjective symptoms and objective signs of vaginal atrophy in menopause: A systematic review of randomised controlled trials. J Obstet Gynaecol. 2016;36(2):160-171.

REFH Obesity

REFH1 Akhlaghi M, Zare M, et al. Effect of Soy and Soy Isoflavones on Obesity-Related Anthropometric Measures: A Systematic Review and Meta-analysis of Randomized Controlled Clinical Trials. Adv Nutr. 2017 Sep 15;8(5):705-717.

REFI Osteoporosis

REFI1 Ricci E, Cipriani S, et al. Soy isoflavones and bone mineral density in perimenopausal and postmenopausal Western women: a systematic review and meta-analysis of randomized controlled trials. J Womens Health (Larchmt). 2010 Sep;19(9):1609-1617.

REFI2 Wei P, Liu M, et al. Systematic review of soy isoflavone supplements on osteoporosis in women. Asian Pac J Trop Med. 2012 Mar;5(3):243-248.

REFJ Type 2 Diabetes

REFJ1 Ding M, Pan A, et al. Consumption of soy foods and isoflavones and risk of type 2 diabetes: a pooled analysis of three US cohorts. Eur J Clin Nutr. 2016 Dec;70(12):1381-1387.

Revision Information

  • Reviewer: EBSCO NAT Review Board Eric Hurwitz, DC
  • Review Date: 02/2020
  • Update Date: 05/27/2020